NIPT (Noninvasive Prenatal Testing): What You Need to Know

If you’re looking for information on noninvasive prenatal testing (NIPT), you’re likely in the first trimester of pregnancy. First, congrats! Take a deep breath and appreciate just how far you’ve already come.

While this time brings both joy and excitement, we know these early days can also spark jitters when your OB-GYN or midwife starts discussing genetic testing. All of a sudden, it gets real for every mama bear who has to choose whether or not to screen for anything that might affect her budding cub.

We understand that these decisions on your journey to parenthood can be tough. But one way to feel more confident is to be well informed. We’ll help you navigate what the NIPT screening test is, as well as what it can (and can’t) tell you — so you’ll feel more empowered to make the best choice for you.

The NIPT prenatal test is sometimes called the noninvasive prenatal screen (NIPS). By 10 weeks of pregnancy, your healthcare provider may talk to you about this elective test as an option to help identify if your baby is at risk for genetic abnormalities, such as chromosomal disorders.

Most commonly, the test determines the risk of disorders such as Down syndrome (trisomy 21), Edwards syndrome (trisomy 18), and Patau syndrome (trisomy 13), as well as conditions caused by missing or extra X and Y chromosomes.

The blood test looks at tiny pieces of cell-free DNA (cfDNA) from the placenta that are present in a pregnant woman’s blood. cfDNA is created when these cells die and are broken down, releasing some DNA into the bloodstream.

It’s important to know that NIPT is a screening test — not a diagnostic test. This means that it can’t diagnose a genetic condition with certainty. It can, however, predict whether the risk of a genetic condition is high or low.

On the positive side, cfDNA also holds the answer to a big question: whether you’re carrying a boy or a girl. Yes, this prenatal test can reveal your baby’s sex in the first trimester — earlier than any ultrasound!

The NIPT is performed with a simple maternal blood draw, so it poses no risks to you or your baby. Once your blood is drawn, it will be sent to a specific lab whose technicians will analyze the results.

Your results will be sent to your OB-GYN or midwife’s office within 8 to 14 days. Each office might have a different policy for delivering results, but someone from your healthcare provider’s staff will likely call you and counsel you from there.

If you’re keeping your baby’s sex a big surprise (even to you) until their “birthday,” remind your medical providers to keep this detail of your NIPT results under wraps.

While optional, the NIPT is usually offered to women based on her OB-GYN or midwife’s recommendations and protocols. However, there are some risk factors that might lead your providers to more strongly recommend it.

a personal or family history of a pregnancy with a chromosomal abnormality

a maternal or paternal chromosomal abnormality

Deciding to have the NIPT screening is a very personal decision, so it’s OK to take the time you need to determine what’s best for you. If you’re having a difficult time, consider speaking to your healthcare provider or a genetic counselor who can help address your concerns and better inform you.

The NIPT measures the fetal cfDNA in the mother’s bloodstream, which comes from the placenta. This is called the fetal fraction. For the most accurate test results possible, the fetal fraction must be over 4 percent. This usually happens around the 10th week of pregnancy and this is why the test is recommended after this time.

There are several ways the fetal cfDNA can be analyzed. The most common way is to determine the amount of both maternal and fetal cfDNA. The test will look at specific chromosomes to see if the percentage of cfDNA from each of these chromosomes is considered “normal.”

If it falls within the standard range, the result will be “negative.” This means the fetus has a decreased risk of the genetic conditions caused by the chromosomes in question.

If the cfDNA is more than the standard range, this could lead to a “positive” result, meaning the fetus may have an increased risk of a genetic condition. But please be reassured of this: NIPT is not 100 percent conclusive. Positive results require further testing to confirm any true-positive fetal chromosomal abnormality or related disorder.

We do also have to mention that there is also a very low risk of getting a false negative NIPT result. In this case, a baby could be born with a genetic abnormality that was not detected with the NIPT or additional screenings throughout the course of pregnancy.

According to this 2016 study, NIPT has a very high sensitivity (true positive rate) and specificity (true negative rate) for Down syndrome. For other conditions such as Edwards and Patau syndrome, the sensitivity is slightly lower but still strong.

It’s important to reiterate, however, that the test is not 100 percent accurate or diagnostic.

This article published in 2015 documents several explanations for false positive and false negative results, such as low fetal levels of cfDNA, vanishing twin, a maternal chromosome abnormality, and other genetic anomalies that occur within the fetus.

In this 2016 study on false negative NIPT results, it was determined that for every 1 in 426 samples of people at high risk for common chromosomal abnormalities, a trisomy 18 (Edwards syndrome) or trisomy 21 (Down syndrome) is undiagnosed due to specific biological differences within the chromosome itself.

False positive NIPT screening results can happen as well. If you have a positive NIPT result, your healthcare provider will likely order additional diagnostic tests. In some cases, these diagnostic tests reveal that the baby doesn’t have a chromosomal abnormality after all.

The CVS test takes a small sample of cells from the placenta, whereas amniocentesis takes a sample of amniotic fluid. Both tests can determine if the fetus has any chromosomal abnormalities with more diagnostic certainty.

Because these two tests can bring the small risk of a miscarriage, they’re recommended selectively and cautiously based on the collaborative decision between you and your medical team.

That said, there are additional noninvasive screenings that might be suggested, including the first trimester risk assessment usually done at 11 to 14 weeks, the quad screening at 15 to 20 weeks, and at 18 to 22 weeks, the fetal structural survey performed via ultrasound.

The NIPT prenatal test is a trusted elective screening tool used to assess the genetic risk of a fetal chromosomal abnormality, such as Down syndrome, in the first trimester of pregnancy.

It’s often more strongly suggested when an expecting mother has risk factors for these genetic disorders. While the test isn’t diagnostic, it can be an informative step toward knowing more about your baby’s health — and sex, too!

Ultimately, the NIPT is your choice, and it can have an emotional impact on anyone who is considering the test. If you have any questions or concerns about the NIPT screen, talk to your trusted OB-GYN or midwife for guidance and support.